A storyboard from the Justice League Snyder Cut version has leaked online which is said to be by DC Comics artist Jim Lee and features Knightmare Batman, played by Ben Affleck.
Note: Possible spoilers follow for the Snyder Cut.
The storyboard makes mention "End Part One," so this looks to possibly be the final scene or even a post-credit scene from Zack Snyder's version of Justice League Part 1, as it is known Zack had plans for sequels.
The art reveals the scene takes place five years later with Knightmare Batman leading what's left of the Justice League which includes The Flash dragging what's left of Cyborg making mention that Gotham now belongs to Darkseid.
Snyder Cut Justice League Storyboard Leak:
The text on the Jim Lee Justice League storyboard states:
Five years later.
Sand dunes. Smoldering solar pits. Gothic spires rising from the desert. Once, this was Gotham. Now, like the rest of the Earth, it belongs to Darkseid.
Coming over the dune, post apocalyptic Batman (as seen in BvS), with a ragtag army of rebels – the surviving members of the Justice League walk over the rise of a dune to see the dilapidated Wayne Manor. Batman leads them. Flash drags what’s left of Cyborg behind him. Bruce looks up to the sky, grimly, “We need to get inside before night. He’s coming.”
End Part One
Snyder Cut of Justice League coming to HBO Max
I believe the Justice League storyboard for the Snyder Cut may have been first leaked by Taylor Murphy of the Cultured Nerd who recently leaked that Hulk image from The Avengers: Endgame and said Ben Affleck will be back as Batman on HBO Max, as Murphy said his family works for Warner Bros.
Worth a mention is that because HBO Max greenlit the Snyder Cut, that things may have changed, so this storyboard may or may no longer be a part of the movie.
The Snyder Cut is due to be released next year on HBO Max and will be featured at next month's big DC FanDome virtual con.